Machine for cutting a moving strip of sheet material



April 26 1955 H. M. BROWN 2,707,027

OF SHEET MATERIAL MACHINE FOR CUTTING A MOVING STRIP Filed Oct. 27. 1950 2 Sheets-Sheet l ATTO RN EY5 April 26, 1955 H M BROWN 2,707,027

MACHINE FOR CUTTING A MOVING STRIP oF SHEET MATERIAL Filed oct. 27, 195o 2 Sheets-Sheet 2 INVENTOR HUM/ARD M. BROWN ATTORNEYS Patented Apr. 2S, 1955 2,707,027 `draw rolls on the one hand and of the cutting cylinder MACHINE FR CUTTING A MOVING STRIP F 5 anisrn cannot be depended upon to maintain changed SHEET MATERIAL speed ratios differing by suiiiciently small increments.

e wear on the coupling elements which link the draw Howard M. Brown, Wood-Ridge, N. J. rolls and the cutting cylinder produces preferred relation- Application october 27, 1950, serial No. 192,539 nlse glgtaidfen y sma epu um Camo e 6 Claims. (CL 164 68) According to the present invention an extremely tine control over the size of the product is obtained by driv- This invention relates to machinery for the cutting of l5 the length of the cut product. Electrical control over a continuous web of sheet material into pieces of uniform the motors which separately drive these members permits size and more particularly to the driving mechanism of extremely line adjustment of the rate of progress of 4which advances the material past a station at which it the web through the machine and past the cutting stais cut. The invention has especial application in the tion. manufacture of rooting material in the form of shingles 2O According to another feature of the invention a basic where the problem of maintaining uniform size of the condition of uniformity is provided for by linking topioduct is rendered acute by the highly abrasive nature gether by means of a xed ratio drive the cutting cyltheieof The invention will be described in terms of its inder and one of the rolls of the draw pair immediately application to a machine for cutting shingles from a conpreceding the cutting station. To a rst approximation tinuous web of roofing material although it is to be therefore the progress of the web past the cutting stauriderstood that it may be applied to the cutting of other tion is made iixed relative to progress past that station materials. of the cutting blades themselves. The effect of wear, A machine for cutting a web of rooting material into wherever occurring, may then be compensated for by varisliingles requires essentially a pair of draw rolls to adation of the torque input to the independently driven roll Vance the material toward a cutting station at a constant of the draw pair and/or by variation of the speed of rate and a rotating cutter to cut the moving sheet into the anvil relative to that of the cutting cylinder. pieces of uniform size. The cuter typically takes the According to another feature of the invention means form of a rotating cylinder having blades affixed to its provided to compare continuously the surface speed surface, shaped according to the desired pattern to be of the anvil with the speed of the cutting cylinder in cut, and a rotating cylinder or anvil against which the order to compensate for wear on the anvil. Such comblades come to bear once for each revolution of the cutparison is preferably accomplished electrically but may ting cylinder. Uniformity in the size of the shingles dealso be accomplished by mechanical means Whose output pends upon uniformity in the rate of passage of the web may be employed to control the application of power through the draw rolls and on constancy in the point of to the anvil. attack between the cutting blades and the web as the web The invention will now be further described by referpasses between the anvil and the cutting cylinder. ence to the accompanying drawings in which:

Wear in either or both of the draw rolls, in the anvil Fig. 1 is a diagrammatic View of a cutting machine acand in the cutting blades produces a slow change in cordng to the present invention. the motion of the web through the machine and in the Fig. 2 is a View in side elevation of a machine emiength of the cut shingles which is highly detrimental to bodying the principles of Fig. 1. the commercial acceptability of the product. For exam- Fig. 3 is a simplified diagram of a form of electrical ple, in the case of strip shingles three feet long, variations control for relating the speed of the anvil of the main length of as little as V32 of an inch which accumulate chine of Fig. l relative to the speed of the cutting cylin their application to a roof are highly objectionable. inder. Thus the length of the shingles must be controlled to an Fig. 4 is a diagrammatic representation of a mechanaccuracy of the order of one art in a thousand. This is ical system for accomplishing the control function elecrendered difficult by the highly abrasive nature of the trically'performed by the apparatus of Fig. 3. material, which usuaily comprises a tar-impregnated felt In Fig. 1 a web 2 is shown emerging at the left from fabric with a coating of fine crushed rock on one side. a forming machine or storage supply through a pair of The material to be cut is thus highly abrasive on one side pull-off rolls 4, not necessarily forming a part of the cutand the abrasive qualities of the two sides usually differ ting machine. Between the rolls 4 and the cutting mamarkedly. For this reason one of each pair of rolls chine the web hangs in a storage loop, from which it through which the finished material is passed is subpasses into the machine overa smoothing roller 8. From jected to more wear than the other. At the same time the smoothing roller the web passes through a pair of the knives which are employed to cut the material are draw rolls 16, thence to a pair of slitting rolls 20 and subjected to a large amount of wear which is somewhat from the slitting rolls to the cutting station between a irregular. cutting cylinder 26 and an anvil 28. After cutting, the ln the shingle cutting machines of the prior art it has shingles are carried away by a take-off assembly 34. been customary to link together mechanically both rolls of In accordance with the principles of the invention the each pair, for example by gears having pitch circles equal two rolls of the draw pair 10 are driven from separate to the initial diameters of their respective rolls. With sources of mechanical power and the anvil 28 is driven uneven accumulation of wear the surface speeds of the from a source of mechanical power distinct from that two members of such a pair get out of step and produce which drives the cutting cylinder 26, the cutting cylinder uneven motion of the material and the lower ioll of the pair l@ being linked to a coml't has further been customary heretofore to drive the 70 mon source of mechanical power. At the same time it cutting cylinder supporting the blades and its mating is highly desirable to provide adjustable speed for the cylinder or anvil by mechanical means distinct from those machine as a whole. Accordingly the machine is preferemployed to drive the draw rolls and to rely upon manably operated from D. C. electric power as shown in ual control to keep the rate of rotation of the cutting Fig. l. The use of D. C. power on the separate driving cylinder and its anvil properly related to the speed of the means supplied to the various elements which advance draw rolls. As an improvement thereon it has been and cut the web facilitates speed change for the machine proposed to link together the draw rolls and the cutting as a whole and makes it possible to keep the various drive cylinder and anvil by some form of variable speed drive. motors in step throughout such speed changes by opera- Changes in the relative speeds of the two pairs of rotat- .tion on a single control.

ing members were then to be made by operating on the S0 D. C. power for the machine is suppliedfrom a motor variable speed drive. I have found however that to hold generator set 1. The generator 13 of this set supplies armature voltage to the various drive motors of the machine. Excitation for the generator 13 and for the drive motors is provided from an excitation source 5 which, like the motor 17 of the motor generator set may be fed from commercially available A. C. power. Electronic rectifiers have been found to be convenient for use in source 5 in place of rotating machines. The various drive motors are separately excited from windings connected (apart from certain resistors and protective devices omitted from the figure for simplicity) across the output of the excitation source. Each of these field windings is provided with its own rheostat for individual speed adjustment of its motor. The motors may also have series compensating windings (not shown). Control of the over-all speed of the machine is provided at the field rheostat 7 of the generator 13 through its iniiuence on the output voltage of the generator.

The smoothing roller 8 is rotated slowly backwards by conventional means not shown so as to present the web in a smooth, taut sheet to the draw rolls 10.

The draw rolls 10 comprise a lower roll 12 and an upper roll 14. In View of its linkage to the cutting cylinder subsequently to be described, the lower roll 12 is the fundamental measuring device of the machine. In order to provide it with maximum wearing qualities it is preferably finished in a hard material such as chrome steel with axial iiutings around its circumference. The liutings insure continuous tracking between the web and the roll 12, subject to a fine adjustment available through the upper roll 14 as will be further described below.

The upper draw roll 14 is supported in suitabl-e mechanism including means for adjustment of its vertical position, and may be advantageously provided with an elastic covering 16 of rubber or similar material. The upper draw roll 14 is driven by a motor 18 which is preferably compound wound in order to permit accurate A machine from a stop. A field rheostat 19 in series with the separate field 21 provides manual control of the field on motor 18 and hence of the torque input to the roll 14, independently of changes in the speed of the machine as a whole. Indication of the performance of the motor 18 may be had by means of a current meter 25 in the armature circuit, the meter being preferably of the center scale null type, capable of indicating current iiow in either direction. Thus the motor 18 may be used either as a source of power for the machine or as a brake, depending on the modification, if any, which it may be desire to make thereby to the progress of the web through the machine. To insure that the motor operate under control, a booster generator 41 driven by a constant speed A. C. motor 43 may advantageously be connected in series with the armature of the motor 18.

The web is typically manufactured in a width larger than that desired for the final product and a pair of slitting rolls may be provided, following the draw rolls, for the purpose of cutting the web into narrower widths as desired. The slitting rolls include an upper roll 22 against which the actual slitting knives (not shown) of the lower roll 24 came to bear. Both rolls of the slitting pair are driven together at the same speed which is preferably above the linear speed of the sheet. Since they are without effect on the motion of the web through the machine, they may without disadvantage be linked mechanically together.

The sheet advanced by the draw rolls 10 is cut transversely of its length by the cutting cylinder 26 in cooperation with a backing roll o`r anvil 28. The cutting cylinder has one or more blades 27 atiixed to its periphery, shaped according to the form desired for the finished shingles. Thus the blades may extend parallel to the axis of the cylinder 26. or they may include peripheral deviations for the cutting of notches, etc., in the shingles. Each blade thus comes to bear against the anvil 28 onc-e for each revolution of the cylinder 26. The surface of the cylinder 26 between the blades may be set with rubber fingers 31 (Fig. 2) of approximately the same height as the blades so as to provide a continuous carrying surface for the web. The anvil, which is a hard finished roll, is supported above the cutting cylinder by mechanism which may be similar to that employed for the support of the upper draw roll 14.

As indicated by the dotted line 30 the cutting cylinder 26 and the lower draw roll 12 are mechanically linked to each other and driven from a single source 18 will at all times r ol mechanical power comprising the motor 32. By its operation of the lower draw roll 12 the motor 32 provides a part, at least, of the energy required to draw the sheet through the machine as well as the energy required to drive the cutting cylinder. The slitting rolls may also be linked to the same source of power. The linkage diagrammatically indicated by the dotted line 30 may take the form of gears or a chain and sprocket drive dimensioned to provide the same peripheral speed to the lower draw'roll 12 and to the effective circumference of th-e cutting cylinder at which are located the cutting blades.

rThis linkage of the draw rolls and cutting cylinder insures that for every inch of peripheral motion of the knives the web to be cut will be advanced by an equal distance, except for a fine control available for'correction purposes at the draw rolls by virtue of the separate drive motor 18. Precisely however the fact that the cutting blades must pass through the sheet and the fact they are subject to severe wear from the abrasive material being cut renders the effective diameter of the cutting cylinder somewhat indeterminate. Manual control of the torque input to the upper draw roll 14 at the field control 19, and automatic and manual control of the speed of the anvil cylinder 28 are therefore provided to permit compensation for the wear of the knife blades and of the anvil.

The anvil is driven by a drive motor 36 energized like the others from the motor generator set 1 and the excitation source 5. It includes however, in the embodiment of Fig. l, an additional field winding 33 for regulation purposes. The winding 33 is excited by the output of a regulating device 38 which compares the surface speed of the anvil with the angular speed of the cutting cylinder 26. For this purpose a surface speed pickup unit 44 is applied to the surface of the anvil. In the embodiment of Figs. 1 and 2 the unit 44 drives a tachometer generator 40 in accordance with the surface speed of the anvil, regardless of the changes 1n its diameter due to wear. A similar tachometer generator 42 is linked to the cutting cylinder via the motor 32, and its output is fed to the regulating device 38 for comparison with that of the generator 40. The tachometer generator 42 is most conveniently linked to the angular rather than to the surface speed of the cylinder 26 in View of the difliculty of measuring the instantaneous diameter of a rotating knife or knives. The tachometer generators conveniently take the form of permanent magnet-excited D. C. generators whose output voltage is an accurately known function of their speeds.

The regulating device 38 includes means to generate from commercial A. C. electric power an excitation voltage for application to the regulating winding 33. The magnitude of this voltage is controlled by the magnitude and sign of the difference between the tachometer generator outputs. Biasing means in the regulating device operated by a control 47 makes possible a preference of one generator output over the other. By suitable adjustment of this biasing means it is thus possible to maintain either equality or any desired inequality between the speeds of the motors 32 and 36.

One form of regulating device is illustrated in simplified form in Fig. 3, enclosed within the dashed line box 38. The tachometer generators 40 and 42 are connected respectively to potentiometers 46 and 48 in voltage opposing relation. The difference between their two voltages is amplified in a direct-current amplifier S0 whose output signal is applied to the control grid of a rectifier 52 of the gas-filled type which supplies the excitation to the regulating field 33 of the anvil motor 36. Adjustment of the potentiometer 46 (as by the control 47) and of the potentiometer 48 makes possible any desired discrirnination in favor of either the anvil or the cutting cyl- 1n er.

In place of the electrical system illustrated in Fig. 3 a mechanical system may be employed for regulation of the anvil motor 36, as shown in Fig. 4. Thus the surface speed pickup unit 44, and the cutting cylinder may be linked mechanically with two limbs of a set of differential gears 54 whose third limb may be linked to a rheostat 37 connected in series with the eld of the anvil motor. In such case it may be sufficient to employ for the motor 36 one field winding 39 on which the rheostat 37 operates directly. Initial adjustment of the 2,707,027' position of the movable contact on the field rheostat 37 2. I n a machine for cutting a web of flexible material here corresponds to adjustment of the potentiometers 46 into pieces of uniform length, two draw rolls, a rotating and 48 of the device of Fig. 3. ife, a rotating cylindrical anvil supported opposite -the A side elevation of a machine embodying the invention knife, a first drive means linked to the rotating knife is shown in Fig. 2. The upper draw roll 14 is shown sup- 5 and to one of the draw rolls, a second drive means linked ported in ways 15 in which it may be raised or lowered to the other of the draw rolls, a direct-current motor for control of the pressure between the rolls by means of linked to the anvil, means to generate a signal repret e anvil above the cutting cylinder is adjusted by a similar generate a signal iepresentative of the speed of the knife cylinder 23, with protection afforded by a mechanical l means to compare said signals and to adjust the excitation stop generally indicated at 29. of said direct-current niotor in accordance with the 0n setting up the machine, as for example after a difference between said signals. change of cutting knives or in response to a change in 3. In a machine for cutting a web of iiexible material the material to be cut, the knife blades are set on the into uniform engths, two draw rolls, a rotating knife, cutting cylinder so that their peripheral speed is the same a rotating anvil against which the knife comes to bear as that of the lower draw roll 12. When the roll 12 and once for each revolution of the knife, means to drive one cylinder 26 are of different diameters the linkage between of the draw iolls and the knife at fixed relative angulai them (30 in Fig l) is of course dimensioned accordingly. speeds, sepaiate means to drive the other draw roll sep- At t e same time the pressure between the draw rolls is arate means to diive the anvil, and means to compare adjusted to preclude any tendency of the web to creep the surface speed of the anvil with the speed of the knife with respect to either of the rolls For this condition a and to maintain a desired relation therebetween. relatively high pressure is required. The separate field 4. ln a machine for cutting a web of flexible roofing of the motor 18 is adjusted so that that motor draws material into uniform shingles, a rotating anvil, a rotatcurrent, as seen on the meter 25, and assists in driving ing knife adapted to bear against the anvil once for each the web through the machine. revolution of the knife, two draw rolls adapted to feed The sheet will then be drawn through the rolls inch the web to the knife, one of said rolls having a hard siii'- for inch of their peripheral motion. The regulating deface and the other having a yielding surface, means to vice 38, or mechanical equivalent therefore shown in adjust the pressure between the draw rolls, separate Fig. 4, may be adjusted to give to the anvil a slivhtly means to drive the two draw rolls, and means to vary higher peripheral speed than that of the blades on the the torque input to the roll having the yielding surface. cylinder 26 so as to preclude the accumulation of slack 5. n a machine for cutting a web of Ilexible ma in the web between the draw rolls and the cutting station. terial into uniform lengths, a rotating anvil, a rotating If the shingles as cut are overlength the progress of the knife adapted to come to beai against the anvil once for web through the machine can be retarded to the desired eac revolution of the knife two draw rolls adapted to (minute) degree by reducing the pressure between the feed the web to the knife, one of the said rolls having raw rolls and by reducing or making negative if necesa hard surface and the other a soft suiface, means to adsary the torque input to the upper draw roll by control just the piessure between the diaw rolls, means to drive of the iield excitation on the motor which drives it. the knife and hard surfaced ioll at fixed relative speeds, ith appropriately reduced pressure between the rolls separate means to drive the soft surfaced roll, means to the resulting troque between them will cause the web to 10 Vary through POSiive and negative Values the torque increep slightly with respect to both, progressing slightly put to the soft surfaced roll, means to compare the stirfaster than the upper roll but more slowly than the lower. faee SPeeC1 0f the lUVii With the Speed 0f the knife, and The plastic covering 16 is of assistance here, especially means to maintain a desired differential between said when the material being cut is thin or of little elasticity. SpeedS- Conversely, if the shingles are short, they may be brought 5- 1H 21 machine f0I' Cutting a Web 0f ieXibie roofing up to the desired length by accelerating the passage of material .into uniform shingles, a rotating anvil, a rothe web through the machine by changing the torque tating knife adapted to come to bear against the anvil input to the upper draw m11 in the Opposite (infection, once for each revolution of the knife, two draw rolls device 38 which controls the relation between the surface 50 having a hard Surface and file 0111er a SOf Surface, meaIlS speed of the anvil and effective peripheial speed of the i0 adjust the PfeSSue between the draw TOUS, means mfe, regardless 0f Wear on the anvl to drive the knife and hard surfaced ioll at fixed relative Similarly, as the knives wear, adjustment to the sepa- Speeds, Separate means 10 dfiVe the Sofi surfaced r011, rately driven draw roll and to the anvil provides eomand means i0 Very through POSifiVe and negative Values pensation in line steps by means of which the cut pieces the OTque iIlPut t0 the SOt surfaced roll. of the web may be .held to the correct length.

ile my irvention has beler described in hterms of References Cited ill the 111e 0f this Patent a particular em odiment, it wil e understood t at variations thereof may be made within the scope of the ap- UNITED STATES PATENTS pended claims. 50 1,635,166 Albee July 12, 1927 Iclaim: 1,991,083 Dean Feb. l2, 1935 l. In a machine for cutting a web of flexible roofing 2,048,754 Putnam July 28, 1936 material into shingles of uniform length, two draw rolls, 2,082,705 LOgan .lune l, 1937 a single rotating knife, a rotating cylindrical anvil sup- 2,085,981 Iversen July 6, 1937 ported opposite the knife, a first drive means linked 2,108,767 FtZgerlld Feb. l5, 1938 to the rotating knife and to one of the draw rolls, a 2,321,057 WeSS June 8, 1943 second drive means linked to the other of the draw rolls, 2,454,021 WISOn Nov. 16, 1948 

